This invention relates to slotted slide plates used in osteosynthesis for repositioning (setting) fractured bones. The plates cause a relative displacement between adjacent bone parts by virtue of a camming effect between sloping slide ramps flanking the plate slot and the head of a screw which passes through the plate slot and is screwed into the bone.
The principle of the slotted slide plates is based on the longitudinal displaceability of the fractured bone parts in the direction of the fracture, whereby a compression effect is achieved. The lowering of the screw head into the slot forces a shift of the broken bone parts.
Slotted slide plates of the above-outlined type are known in a great number of varieties for various fractures, including splinter fractures. In this connection, reference is made to "Osteosynthesepraxis" (Osteosynthesis in Practice) by Frank Schauwecker, published in 1981 by Georg Thieme Verlag, Stuttgart/New York.
The order of magnitude of the achievable displacement paths depends from the thickness of the slotted slide plate and from the slope angle of the slide ramp engaged by the screw head. Both parameters, however, are limited for medical and geometrical reasons. Therefore, subsequent tightening by means of a plate tightening tool can often not be avoided. Such an externally applied plate tightening tool is, however, disadvantageous, in that it tends to enlarge the wound area and might make additional bone drilling necessary. Furthermore, the prolonged time needed to perform the surgery is also a drawback.